Concentric Constant Velocity Coupling for Lower Friction and Inertia
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Solution Overview
Problem
Existing constant velocity joints used in heavy-duty applications like marine propulsion and bulldozers are unreliable, experience high friction losses, and can fail uncontrolled due to inertial forces, leading to safety concerns and inefficiencies.
Innovation Solution
A concentric double coupling design with inner and outer annular members and intermediate members, where the outer annular member of one coupling serves as the inner member of the other, allowing for reduced friction and inertial forces through strategically placed axles and materials like steel and aluminum alloys, ensuring containment of power transmission failures and maintaining concentricity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a double cardan joint with self-centring mechanism is used to link off-set drive shafts, then constant velocity output is achieved, but the joint becomes very heavy with high inertia forces and considerable friction losses
Solution Approach 1:
The joint is divided into two separate concentric couplings (inner and outer) instead of a single integrated mechanism. Each coupling handles specific rotational constraints independently, allowing the system to achieve constant velocity while reducing overall mass and inertia forces through distributed functionality.
Solution Approach 2:
The inner coupling is nested concentrically within the outer coupling, with the outer annular member of the first coupling serving as the inner member of the second coupling. This nested arrangement reduces the overall footprint and allows shared structural elements, decreasing material usage and weight while maintaining the self-centring capability for constant velocity output.
2Reliability
If a double cardan joint with self-centring mechanism is used, then constant velocity output is achieved, but friction losses are considerable
Solution Approach 1:
By segmenting the joint into two separate couplings with distinct intermediate members, each interface requires its own axle connection. This segmentation allows for optimized bearing arrangements at each interface, reducing friction losses compared to a single complex self-centring mechanism.
Solution Approach 2:
Intermediate members are introduced between the inner and outer members of each coupling, constrained by axles. These intermediary elements facilitate smooth relative rotation with reduced friction compared to direct contact arrangements, while still enabling the constant velocity function through the concentric coupling geometry.
3Reliability
If a double cardan joint with self-centring mechanism is used, then constant velocity output is achieved, but the joint can fail in an uncontrolled manner leading to extensive damage
Solution Approach 1:
The failure modes are segmented and contained within each coupling. If one coupling fails, the other remains intact and functional, preventing catastrophic uncontrolled failure. The modular structure isolates potential failure points, limiting damage propagation.
Solution Approach 2:
The concentric double coupling design inherently provides backup functionality. The nested structure with shared common annular member creates redundant load paths, cushioning against sudden failures and preventing the uncontrolled failure modes characteristic of single-joint designs.
4Ease of operation
If a double yoke joint is used, then smooth operation is achieved, but the joint is unreliable and can break apart due to wear and centrifugal loadings
Solution Approach 1:
The double yoke joint is segmented into two separate couplings with intermediate members constrained by axles. This segmentation replaces the unreliable yoke connections with more robust axle-constrained interfaces, maintaining smooth operation while significantly improving reliability under centrifugal loads and wear conditions.
Solution Approach 2:
Intermediate members serve as mediators between the inner and outer members, replacing the direct yoke connections that are prone to failure. These intermediary elements, constrained by axles, provide more reliable load transmission while maintaining the smooth constant velocity operation characteristic of double yoke joints.
Data Source
AI summary
A constant velocity joint comprising two concentric couplings, a first coupling comprising an inner member, an intermediate annular member and an outer annular member, the members being concentric. The inner member of the second coupling is common to the outer member of the first coupling. The members of the couplings are constrained to rotate one with respect to another and the outer member of the second coupling is constrained to rotate angularly in respect of the common member in a way that is the mirror image of the rotation of the inner member with respect to the common member.